A Low-Complexity PAPR Reduction Technique for LTE-Advanced Uplink with Carrier Aggregation

In LTE-Advanced, carrier aggregation (CA) is a key enabling technique to increase the peak data rates of users and enhance the mobility management in heterogeneous networks (HetNets) using dual connectivity solutions. Several CA schemes have been proposed with a maximum of five LTE Release 8 component carriers (CCs) where the NxSC-FDMA has been chosen as the bandwidth extension scheme for the uplink. This enables the extension of the bandwidth allocated to a user up to 100 MHz while maintaining backward compatibility with LTE release 8 legacy users. However, CA leads to a severe increase in the peak-to-average-power ratio (PAPR) of the aggregated time domain NxSC-FDMA signal at the user equipment (UE). This is an important issue as it affects the power amplifier (PA) efficiency and hence the coverage of transmissions. In this paper, we propose a low-complexity post-IFFT technique to reduce the PAPR of carrier aggregated NxSC-FDMA signals in the uplink of LTE-Advanced. Several case studies of CA were analyzed by using the proposed technique. Simulation results show that the PAPR improvement is 2.5 dB for the case of 2 CCs at only about 4% of the complexity required by the partial selective mapping (PSLM) technique to achieve the same PAPR reduction.